New Delhi: Scientists researching extreme rainfall events in India have concluded that more research is needed to understand the human impact on extreme rainfall. The researchers from Indian Institute of Science (IISc) in Bangalore say that the country needs to fine tune its models to simulate hydroclimatic variables at the regional level.

“Studies like this are essential for framing policies for different eventualities under a changing climate. The results of our study can also influence how we manage our water resources,” said Arpita Mondal, now an assistant professor at Indian Institute of Technology, Bombay. Mondal was a part of the research at IISc working with P. P. Mujumdar from the department of civil engineering.

Scientists across the world have attempted to quantify human effects in the components of the water cycle at large scales, including rainfall extremes. Mondal has been studying the changes in extreme rainfall events in India in the past century. The researchers found that although it was clear that they have become more common in the last century, it was not clear how much of this could be attributed to human induced climate change.

Using mathematical models, the researchers analyzed rainfall data from 1,800 rain gauges put up by India Meteorological Department across the country. They focused on very heavy rainfall received in one day and in a span of five days which are likely to have more impact, such as floods. Using detection and attribution analysis, they tried to understand the impact of how human activities influence extreme rainfall events in the country.

The findings of the study suggested that model simulations may underestimate the response of regional climate system to increasing human activities for extremes. The study further said that though anthropogenic factors may have a role to play in causing changes in extreme precipitation, their detection is difficult at regional scales and not statistically significant.

It is already known that rising temperatures can be linked to extreme rainfall by resulting in higher moisture absorbing capacity of the atmosphere. But the researchers wanted to understand the kind of impact factors such as urbanization may have on the phenomenon.

“The international disaster mitigation funding agencies might soon want to quantify human causes behind loss and damage involved in individual hazardous events. Therefore, in future, we would like to investigate how best we can integrate available techniques and modelling tools in both physics and statistics to understand how hydroclimatic extremes change and how anthropogenic activities might possibly influence them,” said Mondal.